Faults involving ground produce high fault current magnitude especially when the transformer(s) neutral is solidly grounded. The neutral ground circuit in the transformer provides the return path for the fault currents. To limit this current, impedance – either in the form of a reactor or a resistor – is installed in the neutral circuit. See [...][Continue Reading...]

In the realm of protective relaying, overcurrent protection is the simplest and an essential scheme. Phase and residual protection are quite common in the industry. Phase elements should be set carefully so as to afford protection for equipment downstream of it while not limit the load current in anyway. Residual currents can be set more sensitive than phase relays since they do not limit the load current. Between these two, it is easy to forget the negative sequence protection.[Continue Reading...]

These terms were coined over a time period to identify the appropriate short circuit current magnitude that engineers could use to size the switchgears, switchboards, panelboards, and the circuit breakers.[Continue Reading...]

The complete article written by Steve Coleman and Aleen Mohammed (PeGuru admin) is published in the Electrical Construction & Maintenance magazine. Read this article on ECMweb at: http://ecmweb.com/arc-flash/arc-flash-hazard-evaluation Article Abstract: If you are conducting an arc flash study, you are probably using one of the many software packages that can perform the analysis for you [...][Continue Reading...]

Arc flash hazard is a huge concern in areas where you are operating medium voltage (1kV - 34kV) and low voltage (less than 1kV) equipment. Mostly because, when you inadvertently initiate a fault, an arc flash ensuing it releases enormous amount of heat energy. The composition of this arc includes molten bits of copper or aluminium busbar or cable.[Continue Reading...]